1. Field of the Invention
The present invention relates to an air intake device of an internal combustion engine.
2. Description of the Prior Arts
An air intake device of an internal combustion engine that utilizes the dynamic effects of the air flow to improve the volumetric efficiency of the engine is known, for example, from Japanese Examined Patent Publication No. 47-43374 issued on Nov. 2, 1972 and Japanese Unexamined Patent Publication No. 55-87821. This known device comprises a tank providing a volumetric area extending along an intake tube, a valve disposed in an interconnecting portion between the tank and the intake passage, and valve activating means to open or shut the valve in response to the engine load. This arrangement makes it possible to enhance engine perfomance.
Analysis of the effect of such a device has determined that an air inlet pipe placed upstream of an air cleaner should be as short as possible, to obtain the most enhanced dynamic effect. However, it has been also determined that there is an increase in the noise from the air intake if the inlet pipe upstream of the air cleaner is cut too short.